Current optical imaging systems are pure optical systems which use optical focusing as a basic technology to image objects directly. One of the characteristics of the current optical system is its relatively limited depth-of-field (DOF), which causes the image of an object out of DOF blurred, and thus the content of image information is not sufficient. The reason is that the current optical imaging systems are linear space variant systems, and the imaging response of the system is strongly relevant to object distances.
An optical imaging system is disclosed in the U.S. Pat. No. 5,748,371A of CDM Optics inc. and its successor. A wavefront coding device disclosed in U.S. Pat. No. 5,748,371A, i.e., a wavefront coding mask component, is a core technology of patents related to wavefront coding owed by CDM Optics INC. The wavefront coding mask device is a phase mask which is constructed by orthogonalizing two odd continuous curved lines or by rotating said lines by 180°. The drawback of the wavefront coding mask component lies in its asymmetry and the high cost in manufacturing and assembling as well as the distorted imaging position of scenery from the ends of DOF caused by the asymmetry.
The international application WO2008/129541A2 of Tel-Aviv university from Israel discloses a wavefront coding device, which is characterized in that a phase mask of the wavefront coding device is based on at least one rotational symmetrical curved surface and includes at least one rotational symmetrical curved surface part for wavefront phase coding and one rotational symmetrical shutter surface part for amplitude coding. The technology is very complicated and causes a high cost in manufacturing.